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Title: The influence of sodium dodecyl sulphate on the dissolution of hydrophobic drugs
Author: Mall, Sukminder
ISNI:       0000 0001 3617 5599
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 1996
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The purpose of this study was to investigate the influence of the anionic surfactant, sodium dodecyl sulphate, on the dissolution of hydrophobic drugs. The surface energy of each drug studied was considered in terms of a Lifshitz-van der Waals contribution and a polar contribution which was divided into electron donor and electron acceptor parameters. These data were obtained from contact angle experiments, using an automated Wilhelmy plate technique. The surface energy data for the solids were used along with surface energy terms for the head groups and the hydrophobic tails of the micelle to give a free energy of adhesion to each region of the micelle for each of the drugs. The solubilities of these drugs were considered in both water and aqueous micellar sodium dodecyl sulphate solutions, as a function of temperature, and also by considering parallel experiments in which the pH was buffered at the pKa of the drug. A Taylor-Aris diffusion technique was also used to provide a direct measurement of partition between a buffered aqueous phase and the micelles, again as a function of temperature. The thermodynamics of transfer were calculated for each experimental procedure by use of the van't Hoff isochore. The initial rotating disk dissolution rate of drug compacts was measured in water and water with SDS micelles at a range of temperatures. The thermodynamic parameters of activation were calculated from the rate data. Correlations were obtained between the measured solubilities, partitioning and dissolution data and the free energy of adhesion obtained from surface energy data. These properties were found to be strongly influenced by a polar repulsion energy between the monopolar surfactant head group. This work provides an insight into a possible mechanism of solubilisation, using the Lewis acid-base approach and the prospect of understanding different partitioning behaviour.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available